1. Field of the Invention
The present invention relates to an ink-jet printing head and, more particularly, to a printing head of an ink-jet printing device using a piezoelectric element.
2. Description of the Prior Art
Generally, a conventional ink-jet printing device is provided with a printing head in which an piezoelectric element is used as a drive source, and an ink reservoir for storing ink. The printing head of the printing device comprises an ink chamber for temporarily storing the ink from the ink reservoir, a pressure chamber, and a piezoelectric element. The ink chamber supplies the ink to the pressure chamber, and a droplet of the ink is ejected from the nozzle of the pressure chamber with a pressure change. This pressure change is produced by actuation of the piezoelectric element on the pressure chamber. Japanese Patent Laid-Open Publication No. HEI 4-163152 published on 1992 discloses a stacked piezoelectric ceramic in which a plurality of piezoelectric ceramic plates is stacked through plane electrodes. A stacked piezoelectric ceramic such as that in Publication No. HEI 4-163152 has been recently used as a piezoelectric element.
In FIG. 1A showing prior art, a piezoelectric element 101 is fixed on a printing head 100 which has a pressure chamber 102. Ink 103 is supplied from an ink chamber (not shown) to the pressure chamber 102. When an electric voltage is applied to the piezoelectric element 101, the pressure chamber 102 is constricted by mechanical deformation of the piezoelectric element as shown in FIG. 1B and, consequently, the pressure in the pressure chamber 102 is increased, so that a droplet of ink is forcibly ejected. When actuation of the piezoelectric element 101 is stopped, the piezoelectric element 101 and the pressure chamber 102 are deformed in the opposite direction by inertia, as shown in FIGS. 1C and 1D, and, finally, they return to their original status, as shown in FIG. 1E. The piezoelectric element may be disposed surrounding a jet nozzle duct, as is described in U.S. Pat. No. 4,418,354.
The conventional printing head, however, has the drawback that the manufacturing cost is high because the pressure chamber or the jet nozzle and piezoelectric element must be manufactured separately and a plurality of piezoelectric elements must be installed individually at predetermined locations on a plurality of pressure chambers.